Leak Current Breaker Phase Angle Detection
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Solution Overview
Problem
In industrial settings, accurately detecting leakage current (Igr) arising from earth insulation resistance is challenging due to harmonic distortion currents from long electric lines and inverters, which can lead to false readings and potential functional damage to electronic devices during insulation resistance testing.
Innovation Solution
A leak current breaker system that includes a leakage current detecting means, converting means, amplifying means, harmonic component removing means, phase contrast detecting means, frequency calculating means, phase angle calculating means, and a circuit breaking means to isolate the electric lines based on the detected leakage current component from earth insulation resistance without disrupting the power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If insulation resistance testing is performed using conventional methods, then leakage current can be detected, but power supply must be interrupted causing operational downtime
Solution Approach 1:
The patent enables continuous leakage current detection while maintaining power supply to the circuit under test. The detection system operates simultaneously with the powered circuit, allowing uninterrupted monitoring of insulation resistance without requiring power interruption, thus eliminating operational downtime while maintaining detection capability
2Measurement precision
If leakage current measurement is performed on electronic devices with high component density, then insulation resistance can be checked, but test voltage may damage electronic circuits
Solution Approach 1:
The patent introduces a coupling capacitor as an intermediary element between the test voltage source and the circuit under test. This capacitor blocks direct current while allowing alternating current measurement, enabling insulation resistance testing without applying damaging test voltage directly to sensitive electronic components, thus protecting the circuit while maintaining measurement capability
3Adaptability or versatility
If long electric lines are used to connect electrical devices, then device coverage is increased, but earth capacitance increases causing false leakage current readings
Solution Approach 1:
The patent segments the leakage current into two distinct components: capacitive leakage current (Igc) and resistive leakage current (Igr). By separately identifying and measuring each component through phase angle detection, the system can distinguish between false readings caused by long line capacitance and actual insulation degradation, maintaining measurement accuracy regardless of line length
Solution Approach 2:
The patent changes the measurement parameter from total leakage current magnitude to phase angle of leakage current. By measuring the phase angle between voltage and current, the system can differentiate between capacitive and resistive components, enabling accurate identification of insulation resistance issues even in the presence of long electric lines with high earth capacitance
4Productivity
If inverters with power semiconductor devices are used for high-speed switching, then operational efficiency is improved, but harmonic distortion current increases leakage current readings
Solution Approach 1:
The patent segments the leakage current into capacitive (Igc) and resistive (Igr) components using phase angle detection. This segmentation allows the system to distinguish between harmonic distortion current flowing through capacitance and actual insulation resistance leakage, maintaining detection accuracy despite the presence of inverters generating harmonic currents
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables safe and accurate detection of leakage current (Igr) from earth insulation resistance without damaging connected devices, allowing for timely intervention to prevent short circuits and fires, while operating continuously without power interruptions.
Implementation Method 1
a converting means for converting the leakage current detected by the leakage current detecting means into a voltage
Implementation Method 2
an amplifying means for amplifying the voltage output from the converting means
Implementation Method 3
a first harmonic component removing means for removing a harmonic component from the voltage amplified by the amplifying means
Implementation Method 4
a phase contrast detecting means for detecting a contrast in signal waveform between the voltage from which the harmonic component has been removed
Data Source
AI summary
A leak current breaker is provided which includes a detector (10) to detect a leakage current from electric lines, a first removing unit (12) to convert the detected leakage current into a voltage and a voltage detector (14) to detect a voltage developed in electric lines A under testing, a second removing unit (16) to remove a harmonic component included in the voltage, a phase contrast detector (20) to detect a phase contrast from a signal waveform having the harmonic component removed, a frequency calculator (21) to calculate a frequency occurring on electric lines A on the basis of the signal waveform of the voltage having the harmonic component removed by the second removing unit (16), a phase angle calculator (22) to calculate a phase angle of the leakage current flowing through the electric lines A on the basis of the phase contrast and frequency, a root-mean-square value calculator (24) to calculate a root-mean-square value of the voltage having the harmonic component removed by the first removing unit (12), a calculator (27) to calculate a leakage current component Igr arising from an earth insulation resistance included in the leakage current flowing through the electric lines A on the basis of the root-mean-square value and phase angle of the leakage current, a judging unit (29) to judge whether the leakage current component Igr calculated by the calculator (27) has exceeded an arbitrary value, and a circuit breaker (30) to break the electric lines A on the basis of the judgment made by the judging unit (29).